The Bug:

Iron bars and walls within trail ruins can generate in invalid block states.

In other words, the said iron bars and walls aren't connected to blocks that aren't part of the trails ruins structure.

Here are some examples:

Seed: -3858014195990910859
Coordinates: /execute in minecraft:overworld run tp @s 18546.11 76.09 -13.18 305.53 28.59

Steps to Reproduce:

1. Generate a world with the seed provided above and teleport to the given coordinates.
2. Look closely at the block states of the iron bars or walls.
3. Take note as to whether or not iron bars and walls within trail ruins can generate in invalid block states.

Observed Behavior:

Iron bars and walls can generate in invalid block states.

Expected Behavior:

Iron bars and walls would generate with the correct block states.